Solid lavatory or urinal cleansing compositions are commonly utilized today to clean, deodorize and disinfect toilet water and toilet fixtures. These compositions are typically shaped in the form of "blocks" or "cakes" and are placed by the user in the toilet tank or bowl, or in urinals. The blocks are then designed to slowly dissolve and thereby release part of their active composition over time. It is this time-release attribute which many have found to be invaluable in dispensing functional agents to the water. In many instances, the action of flushing also serves to further dispense the active ingredients.
Solid forms of lavatory cleansing compositions seem to have acquired broader consumer appeal over a diverse array of other product forms such as liquids, powders, and the like. One attribute is their ease of packaging, shipping and handling. Another is their ability to constantly deliver functional material over a specific time period.
Another example of the utility of solid delivery systems is in the microbiostatic or microbicidal treatment of trough water collected as condensate or cooling water for industrial air conditioners. Effective and convenient treatment of the water can be achieved through the placement in the water of a slow dissolving block containing an antimicrobial active ingredient such as a quaternary halide or phenolic structure conventionally noted for their ability to control microorganisms.
Long-chain cellulosic polymers have been used as a major solid component to control dissolution and release of the active ingredients into the pooled water. For example, Barford et al., U.S. Pat. No. 4,269,723 teaches the use of water soluble, water dispersable clays and cellulosics to retard dissolution. Ziek et al., U.S. Pat. No. 4,722,802, also relates to the use of hydrated cellulosics to retard dissolution. In Ziek et al. the advantages of curing the resultant block are also discussed.
Similarly, Bunczak et al., U.S. Pat. Nos. 4,911,858 and 4,911,859, also relate to the use of very high molecular weight polyethylene oxide polymers together with guar gum and calcium salt to form a gelatin matrix that slows dissolution of the solid system. In the '859 patent, this technology is further utilized to deliver iodophor for intended microbial control.
Menke et al., U.S. Pat. No. 4,820,449, relates to the combination of monoalkyl sulfates, fatty acid mono- and di-alkanolamides and inorganic salts for acceptable longevity. Jeffrey et al. in U.S. Pat. No. 4,043,931 seek longevity through the use of mono- or di-alkanolamides of various aliphatic chain lengths and ethylene oxide/propylene oxide block copolymer surfactants of unspecified proportion of the monomer ratio.
There presently exists a need in the art for a solid block, controlled release delivery system without high molecular weight cellulosics, clays and gums, which does not require a special curing process, or very insoluble calcium salts, or very high molecular weight polyethylene oxide polymers, e.g. polyethylene glycols of molecular weight of 250,000 or much higher.